The MBS-10 stereo microscope (III)

In the two previous issues we have been illustrating the power (and sometimes weakness) of the Russian MBS-10 stereo microscope. Hopefully we were able to clarify some widespread misunderstandings as well.

Virtually every microscopy amateur nowadays will be eager not only to observe microscopically but to photograph his or her findings as well - preferrably without the need of DIY artwork.

Old hands will remember those days when camera-microscope adaptation was kind of mystery. Some images contained so-called hot-spots, in other cases concentric rings were to be found on the photo-micrographs. Vignetting and lacking corner-sharpness were omnipresent. There was a persistent danger of investing money in the wrong improvement, be it mechanical or optical.

With respect to MBS-10 photomicrography we opted for a Nex-5N housing, as we liked its high-res tiltable monitor and its focus loupe very much. Of course you might be able to produce similar results with other camera brands as well. But still we would like to explain our set-up with the Sony in a way that some of you might adopt it:

1  MBS-10 Photographic adapter, main part (including mechanical and optical components)
2  MBS-10 Photographic adapter, adjustable tube (hopefully delivered with the main part)
3  MBS-10 Photographic adapter, M42 counter thread (hopefully included as well)
4  Adapter M42 to Pentax K bayonet (purely mechanical, without optics), Ebay
5  Adapter Pentax K bayonet to Sony bayonet (just a thread adapter), Ebay
6  Sony Nex-5 camera housing (please note that a Nex-5N will do much better do to its electronic vibration, free first shutter)

The MBS-10 photographic adapter is far from being everbody's darling. When looking around the web you will come across many statements denying its usability and quality in general, not to speak of more specific complaints like those about vignetting with classical SLR cameras. Most present CCD cameras have smaller CCD chips, as a consequence vignetting appears no more to be the primary problem. In our set-up as shown above all objective magnifications between 1x and 7x work without vignetting. 0.6x is still strongly vignetted and therefore of little practical use in photography.

The image below depicts the MBS-10 photographic adapter which is being mounted just below the MBS-10 stereo microscope head.

This is all you need: adaptation of a Sony NEX camera to the MBS-10 stereo microscope. The lever on the left allows to chose between "all light to the eye-pieces" and "light directed to the camera and the eye-pieces".

It is important to understand that the adapter contains a complex mechanism which is diverting some of the light to the camera without disturbing the visual observation - but at a price. The prism transfer mechanism can be heavily dust-covered and severely misaligned. We think that much of the web criticism is due to the delicacy of the mechanism. The good news is: if everything is well-adjusted you will feel like superman. The bad news is: if one part of the mechanism is misaligned you will have to study it thoroughly in order to understand the adjustments or, alternatively ask a professional to do the job.

Some people are discussing colour changes caused by the prisms' coated glass but we think that this will not make up a big problem in times of manual white balance and computer imaging. As a rule veridical colour representation tends to have a lower ranking in microsopy (in contrast to everyday photography where colour shifts as a rule will be much more evident and disturbing. People even tend to "believe" in those strange colours which are used to artificially embellish scanning elctron microscope images).

How the adapter works: Position 1, adapter not in use (all light is directed towards the eye-pieces).

How the adapter works: Position 2, parallel visual inspection and photography possible. For this sake the microscopic image is diverted through the right prism onto the photo tube.

Now we are prepared for our tardigrade application example. The next image is showing a routine sitation: tiny tardigrades in a petri dish, no cover glass, and some reflexes caused by detritus particles floating on the water surface. The image is depicting two Halechiniscus maritime tardigrades moving on a sand grain (the red arrow is pointing towards one of them). The sand grain in the very center measures about 2 mm in length.

Two sand grains with Halechiniscus maritime tardigrades. The red arrow is pointing towards a tardigrade measuring ca. 0.1 mm in length. Without its black stomach content it would remain invisible. MBS-10 stereo microscope, objective 2x, camera Sony Nex-5, image width ca. 1 cm.

A higher magnification is needed in order to reveal some more detail: in the animation below one tardigrade is stretching out on the left sand grain (lateral tardigrade view), the other is crawling over the right side of the big sand grain (tardigrade top view).

Combination of 5 stereo microscope still images into one "animated GIF" image. Same as above but magnified by factor 3.

In our opinion it is important to note that any stereo microscope (no matter what you pay) will be restricted to a comparatively low resolution. None of the stereo microscope images will show similar detail as a classical laboratory microscope. The physical reason behind is that the Numerical Aperture (i.e. the resolving power) of most stereo microscopes will be in the range between 0.08 and 0.12 whereas the 10x objective of a classical microscope will already reach Numerical Apertures between 0.25 and 0.30. A typical stereo microscopy will resolve a 60µm tardigrade into a 20 to 30 pixel width image whereas the 10x classical objective might resolve it into 60 and more pixels. As a consequence you will need both: a stereo microscopes for searching and for overview, a classical microscope for studying the details.

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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